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#![allow(dead_code)]
use criterion::{black_box, measurement::WallTime, Bencher};
use tracing::{field, span, Event, Id, Metadata};
use std::{
fmt::{self, Write},
sync::{Mutex, MutexGuard},
};
pub fn for_all_recording(
group: &mut criterion::BenchmarkGroup<'_, WallTime>,
mut iter: impl FnMut(&mut Bencher<'_, WallTime>),
) {
// first, run benchmarks with no subscriber
group.bench_function("none", &mut iter);
// then, run benchmarks with a scoped default subscriber
tracing::subscriber::with_default(EnabledSubscriber, || {
group.bench_function("scoped", &mut iter)
});
let subscriber = VisitingSubscriber(Mutex::new(String::from("")));
tracing::subscriber::with_default(subscriber, || {
group.bench_function("scoped_recording", &mut iter);
});
// finally, set a global default subscriber, and run the benchmarks again.
tracing::subscriber::set_global_default(EnabledSubscriber)
.expect("global default should not have already been set!");
let _ = log::set_logger(&NOP_LOGGER);
log::set_max_level(log::LevelFilter::Trace);
group.bench_function("global", &mut iter);
}
pub fn for_all_dispatches(
group: &mut criterion::BenchmarkGroup<'_, WallTime>,
mut iter: impl FnMut(&mut Bencher<'_, WallTime>),
) {
// first, run benchmarks with no subscriber
group.bench_function("none", &mut iter);
// then, run benchmarks with a scoped default subscriber
tracing::subscriber::with_default(EnabledSubscriber, || {
group.bench_function("scoped", &mut iter)
});
// finally, set a global default subscriber, and run the benchmarks again.
tracing::subscriber::set_global_default(EnabledSubscriber)
.expect("global default should not have already been set!");
let _ = log::set_logger(&NOP_LOGGER);
log::set_max_level(log::LevelFilter::Trace);
group.bench_function("global", &mut iter);
}
const NOP_LOGGER: NopLogger = NopLogger;
struct NopLogger;
impl log::Log for NopLogger {
fn enabled(&self, _metadata: &log::Metadata) -> bool {
true
}
fn log(&self, record: &log::Record) {
if self.enabled(record.metadata()) {
let mut this = self;
let _ = write!(this, "{}", record.args());
}
}
fn flush(&self) {}
}
impl Write for &NopLogger {
fn write_str(&mut self, s: &str) -> std::fmt::Result {
black_box(s);
Ok(())
}
}
/// Simulates a subscriber that records span data.
struct VisitingSubscriber(Mutex<String>);
struct Visitor<'a>(MutexGuard<'a, String>);
impl<'a> field::Visit for Visitor<'a> {
fn record_debug(&mut self, _field: &field::Field, value: &dyn fmt::Debug) {
let _ = write!(&mut *self.0, "{:?}", value);
}
}
impl tracing::Subscriber for VisitingSubscriber {
fn new_span(&self, span: &span::Attributes<'_>) -> Id {
let mut visitor = Visitor(self.0.lock().unwrap());
span.record(&mut visitor);
Id::from_u64(0xDEAD_FACE)
}
fn record(&self, _span: &Id, values: &span::Record<'_>) {
let mut visitor = Visitor(self.0.lock().unwrap());
values.record(&mut visitor);
}
fn event(&self, event: &Event<'_>) {
let mut visitor = Visitor(self.0.lock().unwrap());
event.record(&mut visitor);
}
fn record_follows_from(&self, span: &Id, follows: &Id) {
let _ = (span, follows);
}
fn enabled(&self, metadata: &Metadata<'_>) -> bool {
let _ = metadata;
true
}
fn enter(&self, span: &Id) {
let _ = span;
}
fn exit(&self, span: &Id) {
let _ = span;
}
}
/// A subscriber that is enabled but otherwise does nothing.
struct EnabledSubscriber;
impl tracing::Subscriber for EnabledSubscriber {
fn new_span(&self, span: &span::Attributes<'_>) -> Id {
let _ = span;
Id::from_u64(0xDEAD_FACE)
}
fn event(&self, event: &Event<'_>) {
let _ = event;
}
fn record(&self, span: &Id, values: &span::Record<'_>) {
let _ = (span, values);
}
fn record_follows_from(&self, span: &Id, follows: &Id) {
let _ = (span, follows);
}
fn enabled(&self, metadata: &Metadata<'_>) -> bool {
let _ = metadata;
true
}
fn enter(&self, span: &Id) {
let _ = span;
}
fn exit(&self, span: &Id) {
let _ = span;
}
}